The Effects of Exercise Training in Addition to Energy Restriction on Functional Capacities and Body Composition in Obese Adults during Weight Loss: A Systematic Review

Background

Obesity is associated with impairments of physical function, cardiovascular fitness, muscle strength and the capacity to perform activities of daily living. This review examines the specific effects of exercise training in relation to body composition and physical function demonstrated by changes in cardiovascular fitness, and muscle strength when obese adults undergo energy restriction.

Methods

Electronic databases were searched for randomised controlled trials comparing energy restriction plus exercise training to energy restriction alone. Studies published to May 2013 were included if they used multi-component methods for analysing body composition and assessed measures of fitness in obese adults.

Results

Fourteen RCTs met the inclusion criteria. Heterogeneity of study characteristics prevented meta-analysis. Energy restriction plus exercise training was more effective than energy restriction alone for improving cardiovascular fitness, muscle strength, and increasing fat mass loss and preserving lean body mass, depending on the type of exercise training.

Conclusion

Adding exercise training to energy restriction for obese middle-aged and older individuals results in favourable changes to fitness and body composition. Whilst weight loss should be encouraged for obese individuals, exercise training should be included in lifestyle interventions as it offers additional benefits.     

The Effect of Low‐Intensity Exercise Training on Fat Metabolism of Obese Women

Objective: Previous studies have shown that fat metabolism is different in upper body (UB) and lower body (LB) obese women. The present study investigated whether the effect of low‐intensity exercise training on fat metabolism is different in UB and LB obese premenopausal women. Research Methods and Procedures: Twenty‐one healthy, premenopausal women with either LB obesity (waist‐to‐hip ratio of ≤0.79; n = 8) or UB obesity (waist‐to‐hip ratio of ≥0.85; n = 13) participated in the present study. The UB obese women were matched and randomly divided in an exercise training group (UB) and a nonexercising control group (UB‐C). Subjects in the UB and LB groups participated in a low‐intensity exercise training program (40% Vo ₂max) three times per week for 12 weeks. Before and after the intervention, measurements of fat metabolism at rest and during exercise, body composition, and maximal aerobic capacity were performed. Results: Exercise training did not change the respiratory exchange ratio at rest in the UB and LB groups. During exercise, relative fat oxidation increased in the UB group by 19% (p < 0.05), whereas no change in the LB and UB‐C groups was found. Plasma free fatty acid oxidation did not change by exercise training, and nonplasma fatty acid oxidation tended to increase in the UB group compared with the UB‐C group (p = 0.08). Discussion: Low‐intensity exercise training increased the contribution of fat oxidation to total energy expenditure during exercise but not at rest in UB obese women. Exercise training had no significant effect on fat metabolism in the LB obese women.     

Exercise Improves Host Response to Influenza Viral Infection in Obese and Non-Obese Mice through Different Mechanisms

Obesity has been associated with greater severity of influenza virus infection and impaired host defense. Exercise may confer health benefits even when weight loss is not achieved, but it has not been determined if regular exercise improves immune defense against influenza A virus (IAV) in the obese condition. In this study, diet-induced obese mice and lean control mice exercised for eight weeks followed by influenza viral infection. Exercise reduced disease severity in both obese and non-obese mice, but the mechanisms differed. Exercise reversed the obesity-associated delay in bronchoalveolar-lavage (BAL) cell infiltration, restored BAL cytokine and chemokine production, and increased ciliary beat frequency and IFNα-related gene expression. In non-obese mice, exercise treatment reduced lung viral load, increased Type-I-IFN-related gene expression early during infection, but reduced BAL inflammatory cytokines and chemokines. In both obese and non-obese mice, exercise increased serum anti-influenza virus specific IgG2c antibody, increased CD8+ T cell percentage in BAL, and reduced TNFα by influenza viral NP-peptide-responding CD8+ T cells. Overall, the results suggest that exercise “restores” the immune response of obese mice to a phenotype similar to non-obese mice by improving the delay in immune activation. In contrast, in non-obese mice exercise treatment results in an early reduction in lung viral load and limited inflammatory response.     

BMI and Health‐Related Quality of Life in Adults 65 Years and Older

Objective: To examine relationships of BMI with health‐related quality of life in adults 65 years and older. Research Methods and Procedures: In 1996, a health survey was mailed to all surviving participants ≥ 65 years old from the Chicago Heart Association Detection Project in Industry Study (1967 to 1973). The response rate was 60%, and the sample included 3981 male and 3099 female respondents. BMI (kilograms per meter squared) was classified into four groups: underweight (<18.5), normal weight (18.5 to 24.9), overweight (25.0 to 29.9), and obese (≥30.0). Main outcome measures were Health Status Questionnaire‐12 scores (ranging from 0 to 100) assessing eight domains: health perception, physical functioning, role limitations‐physical, bodily pain, energy/fatigue, social functioning, role limitations‐mental, and mental health. The higher the score, the better the outcome. Results: With adjustment for age, race, education, smoking, and alcohol intake, obesity was associated with lower health perception and poorer physical and social functioning (women only) but not impaired mental health. Overweight was associated with impaired physical well‐being among women only. Both underweight men and women reported impairment in physical, social, and mental well‐being. For example, multivariable‐adjusted health perception domain scores for women were 50.8 (underweight), 62.7 (normal weight), 60.5 (overweight), and 52.1 (obese), respectively. Associations weakened but remained significant with further adjustment for comorbidities. Discussion: Compared with normal‐weight people, both underweight and obese older adults reported impaired quality of life, particularly worse physical functioning and physical well‐being. These results reinforce the importance of normal body weight in older age.     

Obesity‐Related Knowledge,Attitudes, and Behaviors in Obese and Non‐obese Urban Philadelphia Female Adolescents

Objectives: To examine relationships between knowledge, attitudinal and behavioral factors, and obesity and to determine how these factors influence obesity status in west Philadelphia female adolescents. Research Methods and Procedures: A matched‐pairs study was conducted with 32 stature‐ and age‐matched pairs of obese (body mass index and triceps skinfold ≥95th percentile of National Health and Nutrition Examination Survey I) and non‐obese (body mass index and triceps skinfold between the 15th and 85th percentiles of National Health and Nutrition Examination Survey I) female African American adolescents (aged 11 to 15 years), selected from a school‐based study sample, based on obesity status and matching criteria. Adolescents were compared on the following measures: physical activity, inactivity, dietary intake, eating attitudes, health behavior knowledge, body image, self‐esteem, and maturation status. Differences between obese and non‐obese females were tested using paired t tests and Wilcoxon matched‐pairs signed‐rank tests. Results: Physical activity, inactivity, and perception of ideal body size emerged as the most important contributory factors to obesity status. There were no statistically significant matched‐pair differences in macronutrient and micronutrient intakes, self‐esteem, eating attitudes, health behavior knowledge, or maturation status of these adolescents. Obese adolescents had significantly lower levels of physical activity, higher inactivity, and a larger perception of ideal body size than non‐obese adolescents. Discussion: Knowledge and attitudinal factors (with the exception of perception of ideal body size) had far less association with obesity than activity‐related behavioral factors. These findings suggest that future intervention strategies should pay particular attention to physical activity, inactivity, and body image attitudes.     

The relationships among exercise behavior, functional ADL, and psychological health in the elderly

The purpose of this study was to examine the relationships among exercise behavior, the ability to live independently as assessed by functional activities of daily living (ADL), and psychological health as measured by the Philadelphia Geriatric Center morale scale, using data from 202 elderly residents aged 70 and living in their own home. The main results obtained from the analysis were as follows. 1. Exercise behavior had a significant effect on functional ADL. In particular, subjects who had been exercising regularly for 6 months or longer had higher functional ADL than subjects who did not exercise. 2. For psychological health, the functional ADL level was statistically significant, whereas exercise behavior was not. 3. Multiple regression analysis showed a positive and significant association between psychological health and functional ADL, but not between psychological health and exercise behavior, gender or family type. The results of this study demonstrated that elderly people's efforts to maintain and enhance their psychological health play important roles in their ability to live independently, and that regular exercise is necessary to an elderly person's ability to live independently.     

Exercise training reduces insulin resistance and upregulates the mTOR/p70S6k pathway in cardiac muscle of diet‐induced obesity rats

Obesity and insulin resistance are rapidly expanding public health problems. These disturbances are related to many diseases, including heart pathology. Acting through the Akt/mTOR pathway, insulin has numerous and important physiological functions, such as the induction of growth and survival of many cell types and cardiac hypertrophy. However, obesity and insulin resistance can alter mTOR/p70S6k. Exercise training is known to induce this pathway, but never in the heart of diet‐induced obesity subjects. To evaluate the effect of exercise training on mTOR/p70S6k in the heart of obese Wistar rats, we analyzed the effects of 12 weeks of swimming on obese rats, induced by a high‐fat diet. Exercise training reduced epididymal fat, fasting serum insulin and plasma glucose disappearance. Western blot analyses showed that exercise training increased the ability of insulin to phosphorylate intracellular molecules such as Akt (2.3‐fold) and Foxo1 (1.7‐fold). Moreover, reduced activities and expressions of proteins, induced by the high‐fat diet in rats, such as phospho‐JNK (1.9‐fold), NF‐kB (1.6‐fold) and PTP‐1B (1.5‐fold), were observed. Finally, exercise training increased the activities of the transduction pathways of insulin‐dependent protein synthesis, as shown by increases in Raptor phosphorylation (1.7‐fold), p70S6k phosphorylation (1.9‐fold), and 4E‐BP1 phosphorylation (1.4‐fold) and a reduction in atrogin‐1 expression (2.1‐fold). Results demonstrate a pivotal regulatory role of exercise training on the Akt/mTOR pathway, in turn, promoting protein synthesis and antagonizing protein degradation. J. Cell. Physiol. 226: 666–674, 2011. © 2010 Wiley‐Liss, Inc.     

Resistance training lowers exercise-induced oxidative stress and homocysteine levels in overweight and obese older adults

Objective: To compare exercise‐induced oxidative stress and levels of homocysteine and cholesterol in normal‐weight and overweight older adults after resistance exercise (RX). Research Methods and Procedures: This interventional study was conducted at a wellness center. Forty‐nine older adults (age range, 60 to 72 years) were stratified by BMI (<25 kg/m² normal weight, ≥25 kg/m² overweight/obese) and then randomly assigned to either a control non‐exercise group or an RX group. The RX group completed a 6‐month training program. Exercise‐induced lipid hydroperoxides (PEROXs) and thiobarbituric‐reactive acid substances, homocysteine, lipoprotein a, cholesterol, and high‐density lipoprotein cholesterol were measured before and after the 6‐month RX program. Results: PEROXs and thiobarbituric‐reactive acid substances were lower in both the overweight/obese and normal‐weight RX‐trained groups compared with control groups (p < 0.05). Homocysteine levels were lower in both overweight/obese and normal‐weight RX groups compared with control groups (p < 0.05). Lipoprotein a, total cholesterol, and high‐density lipoprotein cholesterol were not different in normal‐weight and overweight/obese groups before or after RX. The change in muscle strength was correlated with homocysteine at 6 months (r = ?0.452, p < 0.05), whereas the change in PEROXs was correlated with the change in body fat (r = ?0.329). Discussion: To our knowledge, these data are the first to show that RX reduces exercise‐induced oxidative stress and homocysteine regardless of adiposity, indicating that this protection can be afforded in an older, overweight/obese population as effectively as in healthy older adults. These data suggest that RX may afford some protection against emerging cardiovascular risk factors using a mode of exercise that supports body weight.     

Exercise but not diet-induced weight loss decreases skeletal muscle inflammatory gene expression in frail obese elderly persons.

Many obese elderly persons have impaired physical function associated with an increased chronic inflammatory response. We evaluated 12 wk of exercise (aerobic and resistance) or 12 wk of weight loss (approximately 7% reduction) on skeletal muscle mRNAs for toll-like receptor-4 (TLR-4), mechanogrowth factor (MGF), TNF-alpha, and IL-6 in 16 obese (body mass index 38+/-2 kg/m2) older (69+/-1 yr) physically frail individuals. Vastus lateralis muscle biopsies were obtained at 0 and 12 wk and analyzed by real-time RT-PCR. Body composition was assessed by dual-energy x-ray absorptiometry. Body weight decreased (-7.5+/-1.2 kg, P=0.001) in the weight loss group but not in the exercise group (-0.3+/-0.8 kg, P=0.74). Fat-free mass (FFM) decreased (-2.9+/-0.6 kg, P=0.010) in the weight loss group and increased (1.6+/-0.6 kg, P=0.03) in the exercise group. Exercise resulted in a 37% decrease in TLR-4 mRNA (P<0.05) while weight loss had no significant effect. Additionally, exercise led to a significant (50%) decrease in IL-6 and TNF-alpha mRNA (P<0.05) while weight loss had no effect. Exercise increased MGF mRNA (approximately 2 fold, P<0.05), but weight loss had no effect. In conclusion, exercise but not weight loss had a beneficial effect on markers of muscle inflammation and anabolism in frail obese elderly individuals.     

Pigment Epithelium‐Derived Factor,Insulin Sensitivity,and Adiposity in Polycystic Ovary Syndrome: Impact of Exercise Training

Pigment epithelium‐derived factor (PEDF) is upregulated in obese rodents and is involved in the development of insulin resistance (IR). We aim to explore the relationships between PEDF, adiposity, insulin sensitivity, and cardiovascular risk factors in obese women with polycystic ovary syndrome (PCOS) and weight‐matched controls and to examine the impact of endurance exercise training on PEDF. This prospective cohort intervention study was based at a tertiary medical center. Twenty obese PCOS women and 14 non‐PCOS weight‐matched women were studied at baseline. PEDF, cardiometabolic markers, detailed body composition, and euglycemic—hyperinsulinemic clamps were performed and measures were repeated in 10 PCOS and 8 non‐PCOS women following 12 weeks of intensified aerobic exercise. Mean glucose infusion rate (GIR) was 31.7% lower (P = 0.02) in PCOS compared to controls (175.6 ± 96.3 and 257.2 ± 64.3 mg.m^?2.min^?1) at baseline, yet both PEDF and BMI were similar between groups. PEDF negatively correlated to GIR (r = ?0.41, P = 0.03) and high‐density lipoprotein (HDL) (r = ?0.46, P = 0.01), and positively to cardiovascular risk factors, systolic (r = 0.41, P = 0.02) and diastolic blood pressure (r = 0.47, P = 0.01) and triglycerides (r = 0.49, P = 0.004). The correlation with GIR was not significant after adjusting for fat mass (P = 0.07). Exercise training maintained BMI and increased GIR in both groups; however, plasma PEDF was unchanged. In summary, PEDF is not elevated in PCOS, is not associated with IR when adjusted for fat mass, and is not reduced by endurance exercise training despite improved insulin sensitivity. PEDF was associated with cardiovascular risk factors, suggesting PEDF may be a marker of cardiovascular risk status.     

Late‐life rapamycin treatment reverses age‐related heart dysfunction

Rapamycin has been shown to extend lifespan in numerous model organisms including mice, with the most dramatic longevity effects reported in females. However, little is known about the functional ramifications of this longevity‐enhancing paradigm in mammalian tissues. We treated 24‐month‐old female C57BL/6J mice with rapamycin for 3 months and determined health outcomes via a variety of noninvasive measures of cardiovascular, skeletal, and metabolic health for individual mice. We determined that while rapamycin has mild transient metabolic effects, there are significant benefits to late‐life cardiovascular function with a reversal or attenuation of age‐related changes in the heart. RNA‐seq analysis of cardiac tissue after treatment indicated inflammatory, metabolic, and antihypertrophic expression changes in cardiac tissue as potential mechanisms mediating the functional improvement. Rapamycin treatment also resulted in beneficial behavioral, skeletal, and motor changes in these mice compared with those fed a control diet. From these findings, we propose that late‐life rapamycin therapy not only extends the lifespan of mammals, but also confers functional benefits to a number of tissues and mechanistically implicates an improvement in contractile function and antihypertrophic signaling in the aged heart with a reduction in age‐related inflammation.     

Alogliptin improves survival and health of mice on a high‐fat diet

Alogliptin is a commonly prescribed drug treating patients with type 2 diabetes. Here, we show that long‐term intervention with alogliptin (0.03% w/w in diet) improves survival and health of mice on a high‐fat diet. Alogliptin intervention takes beneficial effects associated with longevity, including increased insulin sensitivity, attenuated functionality decline, decreased organ pathology, preserved mitochondrial function, and reduced oxidative stress. Autophagy activation is proposed as an underlying mechanism of these beneficial effects. We conclude that alogliptin intervention could be considered as a potential strategy for extending lifespan and healthspan in obesity and overweight.     

Exercise‐stimulated interleukin‐15 is controlled by AMPK and regulates skin metabolism and aging

Aging is commonly associated with a structural deterioration of skin that compromises its barrier function, healing, and susceptibility to disease. Several lines of evidence show that these changes are driven largely by impaired tissue mitochondrial metabolism. While exercise is associated with numerous health benefits, there is no evidence that it affects skin tissue or that endocrine muscle‐to‐skin signaling occurs. We demonstrate that endurance exercise attenuates age‐associated changes to skin in humans and mice and identify exercise‐induced IL‐15 as a novel regulator of mitochondrial function in aging skin. We show that exercise controls IL‐15 expression in part through skeletal muscle AMP‐activated protein kinase (AMPK), a central regulator of metabolism, and that the elimination of muscle AMPK causes a deterioration of skin structure. Finally, we establish that daily IL‐15 therapy mimics some of the anti‐aging effects of exercise on muscle and skin in mice. Thus, we elucidate a mechanism by which exercise confers health benefits to skin and suggest that low‐dose IL‐15 therapy may prove to be a beneficial strategy to attenuate skin aging.     

Intensive weight loss program improves physical function in older obese adults with knee osteoarthritis

Objective: Physical function and body composition in older obese adults with knee osteoarthritis (OA) were examined after intensive weight loss. Research Methods and Procedures: Older obese adults (n = 87; ≥60 years; BMI ≥ 30.0 kg/m²) with symptomatic knee OA and difficulty with daily activities were recruited for a 6‐month trial. Participants were randomized into either a weight stable (WS) or weight loss (WL) program. Participants in WL (10% weight loss goal) were prescribed a 1000 kcal/d energy deficit diet with exercise 3 d/wk. WS participants attended health information sessions. Body composition and physical function (Western Ontario and McMaster University Osteoarthritis Index, 6‐minute walking distance, and stair climb time) were assessed at baseline and 6 months. Statistical analysis included univariate analysis of covariance on 6‐month measurements using baseline values as covariates. Associations between physical function and body composition were performed. Results: Body weight decreased 8.7 ± 0.8% in WL and 0.0 ± 0.7% in WS. Body fat and fat‐free mass were lower for WL than WS at 6 months (estimated means: fat = 38.1 ± 0.4% vs. 40.9 ± 0.4%, respectively; fat‐free mass = 56.7 ± 0.4 vs. 58.8 ± 0.4 kg, respectively). WL had better function than WS, with lower Western Ontario and McMaster University Osteoarthritis Index scores, greater 6‐minute walk distance, and faster stair climb time (p < 0.05). Changes in function were associated with weight loss in the entire cohort. Discussion: An intensive weight loss intervention incorporating energy deficit diet and exercise training improves physical function in older obese adults with knee OA. Greater improvements in function were observed in those with the most weight loss.     

Care Giver Perception of Children's Obesity‐Related Health Risk: A Study of African American Families

Objective: To examine care giver perception of children's weight‐related health risk in African American families. Research Methods and Procedures: One‐hundred and eleven families (representing 48 boys and 63 girls) screened for participation in a diabetes prevention study participated. Care givers completed a health awareness questionnaire that assessed their perception of the child's weight, eating habits, appearance, exercise habits, and health risk. The care givers also reported each subject's family history of obesity, diabetes, and other chronic diseases. After a physical examination, height and weight were used to compute an age‐ and sex‐adjusted body mass index for each child. Results: Despite the fact that a substantial number of children were obese (57%) and super‐obese (12%), only 44% of the care givers perceived the child's weight to be a potential health problem. Regression analysis showed that 21% of the variance in parental perception of obesity‐related health risk could be predicted by child age, body mass index, perception of frame size, and perception of exercise habits. Discussion: A number of reasons for the apparent minimization of child health risk are discussed, including cultural differences in the acceptance of a large body habitus, lack of knowledge about the connection between childhood obesity and future health risk, and an optimistic bias in the perception of personal health risk.     

Regular Aerobic Exercise,Without Weight Loss,Improves Endothelium‐dependent Vasodilation in Overweight and Obese Adults

Lifestyle modification in the form of weight reduction by caloric restriction alone or in combination with regular aerobic exercise significantly improves endothelium‐dependent vasodilation in overweight and obese adults. We determined whether regular aerobic exercise, independent of weight loss, improves endothelium‐dependent vasodilation in overweight and obese adults. Twenty overweight and obese adults (age 53 ± 1 years; BMI: 30.2 ± 0.8 kg/m²) were studied before and after a 3‐month aerobic exercise training intervention. Forearm blood flow (FBF) responses were determined (via plethysmography) in response to intra‐arterial infusion of acetylcholine and sodium nitroprusside. There were no changes in body mass or composition with the intervention. FBF responses to acetylcholine were ～35% higher (P < 0.01) after (4.1 ± 0.9 to 14.7 ± 4.3 ml/100 ml tissue/min) compared with before (4.2 ± 0.8 to 11.0 ± 3 ml/100 ml tissue/min) exercise training. FBF responses to sodium nitroprusside were unchanged. These results indicate that regular aerobic exercise improves endothelium‐dependent vasodilation in overweight and obese adults, independent of changes in body mass or composition.     

Exercise and diet enhance fat oxidation and reduce insulin resistance in older obese adults.

Older, obese, and sedentary individuals are at high risk of developing diabetes and cardiovascular disease. Exercise training improves metabolic anomalies associated with such diseases, but the effects of caloric restriction in addition to exercise in such a high-risk group are not known. Changes in body composition and metabolism during a lifestyle intervention were investigated in 23 older, obese men and women (aged 66 +/- 1 yr, body mass index 33.2 +/- 1.4 kg/m(2)) with impaired glucose tolerance. All volunteers undertook 12 wk of aerobic exercise training [5 days/wk for 60 min at 75% maximal oxygen consumption (Vo(2max))] with either normal caloric intake (eucaloric group, 1,901 +/- 277 kcal/day, n = 12) or a reduced-calorie diet (hypocaloric group, 1,307 +/- 70 kcal/day, n = 11), as dictated by nutritional counseling. Body composition (decreased fat mass; maintained fat-free mass), aerobic fitness (Vo(2max)), leptinemia, insulin sensitivity, and intramyocellular lipid accumulation (IMCL) in skeletal muscle improved in both groups (P < 0.05). Improvements in body composition, leptin, and basal fat oxidation were greater in the hypocaloric group. Following the intervention, there was a correlation between the increase in basal fat oxidation and the decrease in IMCL (r = -0.53, P = 0.04). In addition, basal fat oxidation was associated with circulating leptin after (r = 0.65, P = 0.0007) but not before the intervention (r = 0.05, P = 0.84). In conclusion, these data show that exercise training improves resting substrate oxidation and creates a metabolic milieu that appears to promote lipid utilization in skeletal muscle, thus facilitating a reversal of insulin resistance. We also demonstrate that leptin sensitivity is improved but that such a trend may rely on reducing caloric intake in addition to exercise training.     

Benefits of Regular Exercise on Inflammatory and Cardiovascular Risk Markers in Normal Weight,Overweight and Obese Adults

Obesity is a worldwide epidemic that increases the risk of several well-known co-morbidities. There is a complicated relationship between adipokines and low-grade inflammation in obesity and cardiovascular disease (CVD). Physical activity practices have beneficial health effects on obesity and related disorders such as hypertension and dyslipidemia. We investigated the effects of 6 and 12 months of moderate physical training on the levels of adipokines and CVD markers in normal weight, overweight and obese volunteers. The 143 participants were followed up at baseline and after six and twelfth months of moderate regular exercise, 2 times a week, for 12 months. The volunteers were distributed into 3 groups: Normal Weight Group (NWG,), Overweight Group (OVG) and Obese Group (OBG). We evaluated blood pressure, resting heart rate, anthropometric parameters, body composition, fitness capacity (VO_2max and isometric back strength), cardiovascular markers (CRP, total cholesterol, LDL-c, HDL-c, homocysteine) and adipokine levels (leptin, adiponectin, resistin, IL-6 and TNF-alpha). There were no significant changes in anthropometric parameters and body composition in any of the groups following 6 and 12 months of exercise training. Leptin, IL-6 levels and systolic blood pressure were significantly elevated in OBG before the training. Regular exercise decreased HDL-c, leptin, adiponectin and resistin levels and diastolic blood pressure in OVG. In OBG, exercise diminished HDL-c, homocysteine, leptin, resistin, IL-6, adiponectin. Moderate exercise had no effect on the body composition; however, exercise did promote beneficial effects on the low-grade inflammatory state and CVD clinical markers in overweight and obese individuals.     

Body Composition Measured by Dual‐energy X‐ray Absorptiometry Half‐body Scans in Obese Adults

Dual‐energy X‐ray absorptiometry (DXA) has become a common measurement of human body composition. However, obese subjects have been understudied largely due to weight and scan area restrictions. Newer DXA instruments allow for heavier subjects to be supported by the DXA scanner, but the imaging area is still smaller than the body size of some obese subjects. In this study, we determined the validity of an automated half‐scan methodology by comparing to the standard whole‐body scans in a cohort of obese volunteers. Fifty‐two subjects whose BMI >30 kg/m² completed whole‐body iDXA (GE Lunar) scans. The resulting scans were analyzed in three ways: the standard whole‐body scan, total body estimated from the left side, and from the right side. Fat mass, nonbone lean mass, bone mineral content (BMC), and percent fat derived from each half scan were compared to the whole‐body scans. Total fat mass, nonbone lean mass, or percent fat was comparable for the whole‐body scans, left, and right side scans (>97% within individuals and >99.9% for the group). The BMC estimate using the right side scan was slightly but statistically higher than the whole‐body BMC (～30 g or 1%, P < 0.001), while the left side scan BMC estimate was lower than the whole‐body BMC by the same magnitude. No significant magnitude bias was found for any of the composition variables. We conclude that the new iDXA half‐body analysis in obese subjects appears to be closely comparable to whole‐body analysis for fat mass, nonbone lean mass, and percent fat.